"There is no substance to the allegations made by this documentary, " a Ryanair spokeswoman said.

In a major undercover investigation, two reporters from the Dispatches programme spent five months secretly filming as members of the cabin crew.

"What they found may make you think twice about flying Ryanair again, " said a C4 statement. "The undercover footage reveals what takes place behind the scenes: security lapses, dirty aircrafts, pilots complaining about the hours they have to fly and exhausted cabin crew."

Ryanair: Caught Napping, Channel 4, 8pm, 13 February